A Coast Guard helicopter stirs snow on the ice near the Coast Guard cutter Mobile Bay on the bay of Green Bay near Sturgeon Bay in March 2007.

The U.S. Coast Guard Cutter Mobile Bay was working Tuesday to open a shipping lane from northern Door County to Green Bay to allow passage of the cement carrier Alpena.

The Alpena was scheduled to be the first ship into Green Bay on Monday, but ice conditions delayed arrival. The cutter Katmai Bay was dispatched to assist with operations, according to the U.S. Coast Guard.

Coast Guard crews were reporting thick ice conditions, with up to 30 inches of ice on the bay around Sturgeon Bay.